Re: [PATCH v4 16/24] clk: mediatek: Add MT8189 topckgen clock support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Use-After-Free of `struct clk` during probe error path and device removal due to asymmetric teardown between devm and manual unregistration.
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--- Patch [16]: [PATCH v4 16/24] clk: mediatek: Add MT8189 topckgen clock support ---
commit 1a2a1cefef48aac7c733656cfc07df67d4760fe4
Author: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>

clk: mediatek: Add MT8189 topckgen clock support

Add support for the MT8189 topckgen clock controller, which provides
muxes and dividers for clock selection in other IP blocks.

> diff --git a/drivers/clk/mediatek/clk-mt8189-topckgen.c b/drivers/clk/mediatek/clk-mt8189-topckgen.c
> new file mode 100644
> --- /dev/null
> +++ b/drivers/clk/mediatek/clk-mt8189-topckgen.c

[ ... ]

> +/* Register mux notifier for MFG mux */
> +static int clk_mt8189_reg_mfg_mux_notifier(struct device *dev,
> +					   struct clk *clk)
> +{
> +	struct mtk_mux_nb *mfg_mux_nb;
> +
> +	mfg_mux_nb = devm_kzalloc(dev, sizeof(*mfg_mux_nb), GFP_KERNEL);
> +	if (!mfg_mux_nb)
> +		return -ENOMEM;
> +
> +	mfg_mux_nb->ops = &mtk_mux_clr_set_upd_ops;
> +	mfg_mux_nb->bypass_index = 0; /* Bypass to CLK_TOP_MFG_REF_SEL */
> +
> +	return devm_mtk_clk_mux_notifier_register(dev, clk, mfg_mux_nb);
> +}

[Severity: High]
This is a pre-existing issue, but does using 
devm_mtk_clk_mux_notifier_register() here introduce a use-after-free during
driver unbinding or probe failure?

If mtk_clk_simple_probe() fails after registering this notifier, or when
the module is removed via mtk_clk_simple_remove(), the manual teardown
functions like mtk_clk_unregister_muxes() execute immediately. This calls
clk_hw_unregister(), which frees the struct clk object.

Later, the driver core initiates devres cleanup and invokes
devm_clk_notifier_release(). This function will call
clk_notifier_unregister() using the already freed clk pointer.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260729-mt8189-clocks-system-base-v4-0-e356b813a64c@collabora.com?part=16